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Zinc homeostasis in Malawian children consuming a high-phytate, maize-based
diet1,2,3
American Journal of Clinical Nutrition, Vol. 75, No. 6, 1057-1061, June 2002
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Background: Zinc deficiency in children is an important public health
concern in the developing world, and the consumption of predominantly
cereal-based diets with a high phytate content may contribute to the risk.
The gastrointestinal tract plays a central role in absorbing and conserving
zinc, yet it has not been carefully studied in such children.

Objective: This study investigated zinc homeostasis in healthy, free-living
Malawian children with habitually high-phytate diets to better understand
the role of the gastrointestinal tract.

Design: We evaluated zinc homeostasis in 10 children aged 2-5 y who were
consuming a maize-based diet (phytate:zinc molar ratio of 23:1). Zinc stable
isotopes were administered orally and intravenously. The tracer and tracee
were measured in urine and feces.

Results: Endogenous fecal zinc was high in comparison with results for this
measure in previous studies. Typical correlations seen in subjects consuming
a low-phytate diet between total absorbed zinc, the size of the exchangeable
zinc pool, and endogenous fecal zinc were not observed. Fractional
absorption of zinc was 0.24.

Conclusions: Zinc homeostasis was perturbed, particularly by large,
endogenous fecal zinc losses, in this vulnerable population. The effects of
interventions to improve zinc status, including dietary phytate reduction,
on zinc homeostasis merit further study.